Interference Screening in Assay Validation

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-27

Quick Answer

Interference screening evaluates how hemolysis, lipemia, and bilirubin affect assay results by comparing spiked samples to baseline measurements.
Use CLSI EP07 principles to prepare interference pools, test clinically relevant concentrations, and calculate percent bias against acceptance limits.
Screening cannot replicate every patient matrix effect, so confirm suspected interference with individual patient samples and document all findings.

At a Glance

Interferent	Typical Source	Screening Approach	Key Consideration
Hemolysis	Red blood cell rupture during collection or processing	Prepare hemolysate by freeze-thaw or mechanical lysis, then spike into sample pools	Free hemoglobin absorbs at wavelengths that may overlap with assay detection
Lipemia	Elevated triglycerides or chylomicrons	Use lipid-rich patient samples or commercial lipid emulsions	Turbidity scatters light and can alter absorbance or light-scatter measurements
Bilirubin	Elevated conjugated or unconjugated bilirubin	Spike purified bilirubin into sample pools	Bilirubin has intrinsic absorbance that can interfere with colorimetric endpoints

Understanding Interference Screening

Interference screening is a core component of assay validation that determines whether substances present in patient samples alter measured results. Clinical laboratory scientists must evaluate how common endogenous compounds affect assay performance before implementing a new method or when modifying an existing one. The Clinical and Laboratory Standards Institute (CLSI) document EP07 provides the framework for interference testing, and this article translates those principles into a practical workflow.

Endogenous interferents are substances naturally present in blood that can affect analytical measurements. Hemoglobin, triglycerides, and bilirubin are the most frequently evaluated because they appear in many patient populations. Hemoglobin is released when red blood cells rupture, which can happen during collection, transport, or processing. Lipemia refers to elevated lipid particles in the blood, often from recent food intake or metabolic conditions. Bilirubin is a breakdown product of red blood cells that rises in liver disease and other conditions.

The practical problem is that these substances can change the measured signal in ways that do not reflect the true concentration of the analyte. A laboratory that does not screen for interference may report results that are clinically misleading. For example, a falsely elevated result could lead to unnecessary treatment, while a falsely decreased result could delay needed care.

The goal of interference screening is to determine whether the assay produces accurate results when these substances are present. The process involves preparing samples with known amounts of the interferent, measuring the analyte, and comparing the results to a baseline sample without the interferent. The difference between the two measurements indicates the degree of interference.

Core Principles of Interference Testing

The Analytical Signal and Interference Mechanisms

Every assay relies on a measurable signal that correlates with the concentration of the analyte. The signal may be absorbance, fluorescence, luminescence, or another physical property. Interferents can affect this signal through several mechanisms. Hemoglobin and bilirubin have intrinsic absorbance in the visible spectrum, which can add to or subtract from the signal generated by the assay chemistry. Lipemia scatters light, which can reduce the amount of light reaching the detector or create a false signal.

The magnitude of interference depends on the assay design. Some assays have built-in correction mechanisms, such as blanking or bichromatic measurements. Others are more susceptible to interference because they rely on a single wavelength or a chemical reaction that is affected by the interferent. The screening process must account for these differences.

The CLSI EP07 Framework

The CLSI EP07 document, titled Interference Testing in Clinical Chemistry, provides a standardized approach for evaluating interference. The document describes how to prepare interference samples, select concentrations, and interpret results. The approach is based on the principle that interference is a systematic error that can be quantified by comparing measurements with and without the interferent.

The EP07 protocol involves several steps. First, the laboratory identifies the interferents that are relevant to the assay and the patient population. Second, the laboratory prepares a baseline sample pool and a series of samples with increasing concentrations of the interferent. Third, the laboratory measures the analyte in each sample and calculates the difference from baseline. Fourth, the laboratory compares the difference to a predefined acceptance criterion.

The acceptance criterion is typically based on the total allowable error for the assay. The laboratory must decide what level of bias is acceptable based on the clinical use of the result. For example, an assay used to monitor a critical medication may have a stricter criterion than a screening test.

Concentration Selection

The concentrations of interferents used in screening should reflect the range that can be observed in patient samples. The CLSI EP07 document recommends testing at least three concentrations, including a baseline with no interferent, a concentration near the upper limit of the normal range, and a concentration that represents a clinically significant elevation. The laboratory should also consider the highest concentration that might be encountered in practice.

For hemolysis, the concentration of free hemoglobin is typically expressed in milligrams per deciliter. A normal sample may have less than 50 mg/dL of free hemoglobin, while a visibly hemolyzed sample can exceed 500 mg/dL. For lipemia, the concentration of triglycerides is used, with normal values below 150 mg/dL and severely lipemic samples exceeding 1000 mg/dL. For bilirubin, the concentration is expressed in milligrams per deciliter, with normal values below 1.2 mg/dL and elevated values exceeding 20 mg/dL.

The laboratory should not assume that the highest concentration is the only one that matters. Some interferers show a nonlinear relationship with the measured signal. A low concentration may produce a small bias that is not clinically significant, while a higher concentration may produce a bias that exceeds the acceptance criterion. The screening must therefore include a range of concentrations to characterize the relationship.

Preparing Interference Samples

Baseline Sample Pool

The baseline sample pool is the starting point for interference screening. The pool should be prepared from patient samples that have low or undetectable levels of the interferent. The pool should also have a known concentration of the analyte that is within the reportable range of the assay. The laboratory should prepare a sufficient volume of the pool to allow for all the spiking experiments and replicate measurements.

The baseline pool should be mixed thoroughly to ensure homogeneity. The laboratory should measure the analyte in the baseline pool multiple times to establish the baseline value and its variability. The baseline value is the reference point for calculating the bias in the spiked samples.

Hemolysate Preparation

Hemolysate is prepared by lysing red blood cells to release hemoglobin. The laboratory can use a freeze-thaw method, in which the sample is frozen and then thawed to break the cell membranes. Alternatively, the laboratory can use a mechanical method, such as sonication or hypotonic lysis. The hemolysate should be prepared from a sample with a known hematocrit so that the hemoglobin concentration can be calculated.

The hemolysate is then added to the baseline pool in increasing amounts. The laboratory should prepare a stock hemolysate with a known hemoglobin concentration and then dilute it into the pool to achieve the target concentrations. The volume of the hemolysate added should be small relative to the pool volume to avoid diluting the analyte.

Lipemic Sample Preparation

Lipemic samples can be prepared by adding a lipid emulsion to the baseline pool. The lipid emulsion should be characterized for its triglyceride concentration. The laboratory should add the emulsion in increasing amounts to achieve the target triglyceride concentrations.

Alternatively, the laboratory can use patient samples with naturally elevated lipid levels. This approach is more realistic but introduces variability because the lipid composition may differ between patients. The laboratory should document the source of the lipemic material and the measured triglyceride concentration.

Bilirubin Spiking

Bilirubin is typically spiked into the baseline pool using a concentrated bilirubin solution. The bilirubin should be dissolved in a suitable solvent, such as dimethyl sulfoxide or a small amount of sodium hydroxide, and then added to the pool. The laboratory should measure the bilirubin concentration in the spiked samples to confirm the target levels.

Bilirubin is light-sensitive and can degrade over time. The laboratory should prepare the bilirubin solution fresh and protect it from light. The spiked samples should be measured promptly after preparation.

Choosing Concentrations and Acceptance Criteria

Clinically Relevant Concentrations

The concentrations of the interferent used in the screening should be based on the clinical context of the assay. The laboratory should consult the literature and the assay manufacturer to determine the concentrations that are relevant to the patient population. The CLSI EP07 document recommends testing concentrations that span the range from normal to severely elevated.

The laboratory should also consider the concentration of the analyte in the baseline pool. The interference may be more pronounced at low analyte concentrations than at high concentrations. The screening should therefore include samples with different analyte concentrations if the assay is used across a wide range.

Acceptance Criteria

The acceptance criterion is the maximum allowable bias that the laboratory is willing to accept. The criterion is typically expressed as a percentage of the baseline value. The laboratory should define the criterion before the screening begins to avoid bias in the interpretation.

The acceptance criterion can be based on the total allowable error for the assay, which is often derived from biological variation data. The laboratory can also use a fixed percentage, such as 10 percent, as a practical threshold. The criterion should be documented in the validation plan.

Interpreting the Results

The bias for each interferent concentration is calculated as the difference between the measured value in the spiked sample and the baseline value, divided by the baseline value. The bias is expressed as a percentage. The laboratory should plot the bias against the interferent concentration to visualize the relationship.

If the bias exceeds the acceptance criterion at any concentration, the laboratory should document the concentration at which the interference becomes significant. This information is used to define the reporting limits for the assay. For example, the laboratory may report a comment that the assay is not reliable for samples with a hemolysis index above a certain level.

Practical Workflow for Interference Screening

Step 1: Define the Scope

The laboratory should identify the interferents to be tested based on the assay method and the patient population. The most common interferents are hemolysis, lipemia, and bilirubin, but other substances may be relevant. The laboratory should also consider the sample type, such as serum or plasma, and the collection tube additives.

Step 2: Prepare the Baseline Pool

The laboratory should prepare a baseline pool from samples with low interferent levels. The pool should be mixed and measured to establish the baseline value. The laboratory should record the pool preparation details, including the source of the samples and the measured analyte concentration.

Step 3: Prepare the Interference Samples

The laboratory should prepare a series of samples with increasing concentrations of the interferent. The samples should be prepared in duplicate or triplicate to assess variability. The laboratory should record the preparation method and the measured interferent concentration for each sample.

Step 4: Measure the Analyte

The laboratory should measure the analyte in the baseline pool and each interference sample using the assay under evaluation. The measurements should be performed in the same run to minimize run-to-run variability. The laboratory should record the raw measurements and the calculated concentrations.

Step 5: Calculate the Bias

The laboratory should calculate the bias for each interference sample using the baseline value as the reference. The bias should be expressed as a percentage. The laboratory should also calculate the standard deviation of the measurements to assess the precision of the assay.

Step 6: Interpret the Results

The laboratory should compare the bias to the acceptance criterion. If the bias is within the criterion at all concentrations, the assay is considered to be free of interference for the tested interferent. If the bias exceeds the criterion, the laboratory should document the concentration at which the interference becomes significant.

Step 7: Document and Report

The laboratory should document the screening results in a validation report. The report should include the assay name, the interferents tested, the concentrations used, the measured bias, and the interpretation. The report should be reviewed and approved by the laboratory director.

Records and Measurements

Data to Record

The laboratory should maintain detailed records of the interference screening. The records should include the date of the screening, the assay name and lot number, the baseline pool preparation, the interferent preparation, the measured concentrations, and the calculated bias. The records should also include the acceptance criterion and the interpretation.

The records should be stored in a format that is accessible for review. The laboratory should retain the records for the period required by the laboratory quality management system.

Quality Controls

The laboratory should include quality control samples in the interference screening. The quality control samples should be measured in the same run as the interference samples to ensure the assay is performing within the expected range. The quality control results should be recorded and reviewed.

The laboratory should also monitor the performance of the assay over time. The interference screening is a one-time validation, but the laboratory should be alert to changes in the assay performance that could indicate a new interference.

Common Failure Patterns

Incomplete Lysis

A common failure in hemolysis screening is incomplete lysis of the red blood cells. If the hemolysate is not prepared correctly, the hemoglobin concentration may be lower than expected, and the interference may be underestimated. The laboratory should verify the hemoglobin concentration in the hemolysate before use.

Bilirubin Degradation

Bilirubin is unstable and can degrade during the screening process. If the bilirubin solution is not prepared fresh or is exposed to light, the concentration may be lower than expected. The laboratory should measure the bilirubin concentration in the spiked samples to verify the target.

Dilution Effects

The addition of the interferent to the baseline pool can dilute the analyte. If the volume of the interferent is large relative to the pool volume, the analyte concentration may be reduced, and the bias may be overestimated. The laboratory should minimize the volume of the interferent added or correct for the dilution.

Nonlinear Interference

Some interferents may produce a nonlinear relationship between the concentration and the bias. The laboratory should test multiple concentrations to identify the shape of the relationship. A single concentration may not be sufficient to characterize the interference.

Limitations and Interpretation

The Screening Context

The interference screening is performed under controlled conditions. The results may not reflect the interference in real patient samples, which can contain multiple interferents and other substances. The laboratory should interpret the screening results with caution and consider the clinical context.

The Need for Confirmatory Testing

If the screening identifies a significant interference, the laboratory should confirm the finding with patient samples. The laboratory should collect samples from patients with known elevated levels of the interferent and compare the assay results to a reference method. The confirmatory testing provides evidence that the interference is clinically relevant.

The Role of the Manufacturer

The laboratory should also review the manufacturer's claims about interference. The manufacturer may have performed interference testing during the development of the assay. The laboratory should compare the manufacturer's data to the laboratory's own screening results.

Biosafety and Regulatory Context

Biosafety Considerations

The interference screening involves the handling of blood samples and the preparation of hemolysates. The laboratory should follow the biosafety principles described in the Biosafety in Microbiological and Biomedical Laboratories (BMBL) document. The laboratory should use appropriate personal protective equipment, such as gloves and a lab coat, and should handle all blood samples as potentially infectious.

The laboratory should also follow the institutional biosafety requirements. The laboratory should have a biosafety manual and a designated biosafety officer. The laboratory should be trained on the safe handling of blood samples and the proper disposal of biohazardous waste.

Regulatory Context

The laboratory should follow the regulatory requirements for assay validation. The laboratory should be accredited by a recognized body, such as the College of American Pathologists or the Joint Commission. The laboratory should also follow the Clinical Laboratory Improvement Amendments (CLIA) regulations for quality control and validation.

The laboratory should be aware of the regulatory requirements for the specific assay. Some assays may have additional requirements, such as the need for a specific validation protocol or the use of a reference method.

Professional Escalation Criteria

The laboratory should escalate the interference screening results to the laboratory director or the clinical team if the interference is significant. The escalation should include the screening data and the interpretation. The laboratory should also escalate if the interference is not expected based on the manufacturer's data.

The laboratory should also escalate if the interference screening reveals a problem with the assay that cannot be resolved. The laboratory may need to contact the manufacturer or the clinical team to determine the appropriate action.

Building a Structured Interference Screening Decision Framework

Interference screening generates a substantial amount of data, and the practical challenge for laboratory scientists is converting that data into defensible decisions about assay usability. A structured decision framework helps standardize the interpretation process, reduces the risk of inconsistent judgments between analysts, and provides a clear audit trail for regulatory review. This section presents a tiered decision framework that integrates with the CLSI EP07 workflow described earlier, adds a structured approach to handling borderline results, and establishes a practical system for documenting interference thresholds that can be applied directly to patient result reporting.

The Tiered Decision Framework

The tiered decision framework organizes interference screening into three distinct levels of evaluation. Each tier answers a different question and requires different types of evidence. This structure prevents the common failure of treating all interference findings as equally significant and helps the laboratory allocate its confirmatory testing resources to the findings that matter most.

Tier 1: Analytical Signal Assessment

The first tier addresses whether the interferent produces any measurable change in the assay signal. This is a purely analytical question that does not yet consider clinical significance. The laboratory compares the measured bias at each interferent concentration to the assay's own precision profile. If the bias at a given concentration falls within the assay's day-to-day coefficient of variation, the interferent is considered to have no detectable effect at that level.

The precision profile should be established from the quality control data collected during the screening run. The laboratory should use the same lot of reagents and the same calibration curve for the precision assessment and the interference measurements. This ensures that the comparison is valid and that the observed bias is not an artifact of run-to-run variability.

For the tier 1 assessment, the laboratory should record the following for each interferent concentration tested:

The measured analyte concentration in the baseline pool
The measured analyte concentration in each spiked sample
The calculated percent bias
The assay coefficient of variation at the relevant analyte concentration
A pass or fail determination for each concentration

The tier 1 determination is a pass when the percent bias is less than the assay coefficient of variation. A fail at this tier means the interferent produces a change that exceeds the assay's inherent variability, and the finding moves to the second tier for clinical evaluation.

Tier 2: Clinical Significance Assessment

The second tier evaluates whether the bias observed in tier 1 is clinically meaningful. This assessment requires the laboratory to define the acceptance criterion before the screening begins. The acceptance criterion is typically based on the total allowable error for the assay, which is derived from biological variation data or from the assay manufacturer's claims.

The laboratory should document the source of the acceptance criterion in the validation plan. For example, the criterion may be based on the CLIA allowable error for the specific analyte, or it may be based on the laboratory's own quality goals. The criterion should be expressed as a percentage of the baseline value and should be applied consistently across all interferents tested.

The tier 2 determination is a pass when the bias at all tested concentrations is within the acceptance criterion. A fail at this tier means the interferent produces a bias that exceeds the clinically acceptable limit at one or more concentrations. The laboratory should record the lowest interferent concentration at which the bias exceeds the criterion. This concentration becomes the interference threshold for the assay.

Tier 3: Confirmatory Testing and Reporting

The third tier is triggered when the tier 2 assessment identifies a significant interference. The laboratory must confirm the finding with patient samples that have naturally elevated levels of the interferent. The confirmatory testing provides evidence that the interference observed in the spiked samples is clinically relevant and not an artifact of the spiking process.

The confirmatory testing should include at least five patient samples with interferent concentrations above the threshold identified in tier 2. The laboratory should measure the analyte in these samples and compare the results to a reference method or to the expected value based on the patient's clinical picture. The confirmatory testing should be documented in the validation report.

If the confirmatory testing confirms the interference, the laboratory must define the reporting limits for the assay. The reporting limits should specify the maximum interferent concentration at which the assay produces reliable results. The laboratory should also develop a comment that is added to patient reports when the interferent concentration exceeds the threshold.

The Interference Threshold and Reporting Limits

The interference threshold is the concentration of the interferent at which the bias exceeds the acceptance criterion. This threshold is the most important output of the screening process because it directly informs the laboratory's reporting policy. The threshold should be recorded for each interferent and each analyte concentration tested.

The laboratory should consider whether the threshold varies with the analyte concentration. Some interferents produce a constant bias that is independent of the analyte concentration, while others produce a bias that is proportional to the analyte concentration. The screening should include samples with different analyte concentrations to characterize this relationship.

The reporting limit is the practical application of the interference threshold. The laboratory should define the reporting limit as the highest interferent concentration at which the assay produces results within the acceptance criterion. For example, if the hemolysis threshold is 300 mg/dL of free hemoglobin, the laboratory should flag all samples with a hemolysis index above 300 mg/dL.

The reporting limit should be communicated to the clinical team. The laboratory should provide the clinical team with a list of the interferents tested, the thresholds, and the reporting comments. This communication ensures that the clinical team understands the limitations of the assay and can interpret patient results accordingly.

The Interference Screening Record System

A structured record system is essential for the interference screening to be reproducible and defensible. The record system should capture the screening design, the preparation details, the measurements, and the decisions. The record system should be designed before the screening begins and should be used consistently throughout the validation.

The record system should include the following components:

Screening Design Record

The screening design record documents the interferents to be tested, the concentrations to be used, the baseline pool preparation, and the acceptance criteria. This record is created before the screening begins and serves as the protocol for the experiment. The record should include the following:

The assay name and the reagent lot number
The interferents to be tested and the rationale for each
The target concentrations for each interferent
The baseline pool preparation details, including the source of the samples and the measured analyte concentration
The acceptance criteria for each interferent

Preparation Log

The preparation log documents the actual preparation of the interference samples. The log should include the date and time of preparation, the method used to prepare the hemolysate or the lipid emulsion, the measured concentration of the interferent in each spiked sample, and the volume of the interferent added to the baseline pool. The log should also include any deviations from the screening design and the reason for the deviation.

Measurement Log

The measurement log records the raw measurements from the assay. The log should include the date and time of the measurement, the instrument used, the calibration status, the quality control results, and the measured analyte concentration for each sample. The log should also include the raw signal values, such as absorbance or fluorescence, if the assay provides them.

Bias Calculation and Interpretation

The bias calculation and interpretation section records the calculated bias for each sample and the comparison to the acceptance criteria. The section should include the formula used to calculate the bias, the calculated bias for each sample, the tier 1 and tier 2 determinations, and the final interpretation.

Confirmatory Testing Record

The confirmatory testing record documents the patient samples used to confirm the interference. The record should include the patient sample identifiers, the measured interferent concentration, the measured analyte concentration, the reference method result, and the comparison of the results.

Troubleshooting the Screening Process

The screening process can fail in several ways. The laboratory should be prepared to troubleshoot the process when the results are unexpected or when the screening does not produce a clear answer. The following troubleshooting steps address the most common failure patterns.

Unexpected Bias at Low Concentrations

If the bias exceeds the acceptance criterion at a low interferent concentration that is not clinically relevant, the laboratory should first verify the interferent concentration in the spiked sample. The interferent may have been added at a higher concentration than intended, or the baseline pool may have contained a higher level of the interferent than expected.

The laboratory should also check the assay calibration. A shift in the calibration curve can produce a bias that is not related to the interferent. The laboratory should review the quality control results for the screening run and repeat the measurements if the quality control is out of range.

No Bias at High Concentrations

If the screening shows no bias at the highest interferent concentration, the laboratory should verify that the interferent was actually added to the sample. The interferent may have precipitated or degraded during the preparation, or the volume added may have been too small to produce a measurable effect.

The laboratory should also consider the assay design. Some assays have built-in correction mechanisms that eliminate the interference. The laboratory should review the assay manufacturer's documentation to determine whether the assay is expected to be free of interference for the tested interferent.

Nonlinear Bias Relationship

If the bias increases with the interferent concentration but the relationship is not linear, the laboratory should test additional concentrations to characterize the relationship. The nonlinear relationship may indicate that the interference is saturable or that the interferent affects the assay through multiple mechanisms.

The laboratory should also consider the possibility that the interferent is affecting the assay through a matrix effect instead of a direct signal interference. The matrix effect can be evaluated by comparing the spiked samples to a sample that has been diluted with the same volume of the interferent solvent.

The Dilution Effect

The addition of the interferent to the baseline pool can dilute the analyte. The dilution effect is a common source of bias in interference screening. The laboratory should minimize the volume of the interferent added to the baseline pool. The volume should be less than 10 percent of the total pool volume.

If the dilution effect cannot be avoided, the laboratory should correct the measured analyte concentration for the dilution. The correction factor is the ratio of the total volume to the volume of the baseline pool. The corrected concentration is the measured concentration multiplied by the correction factor.

The Interference Threshold and Patient Result Reporting

The interference threshold is the basis for the laboratory's patient result reporting. The laboratory should define the reporting policy for each interferent based on the threshold. The policy should specify the following:

The interferent concentration at which the assay is no longer reliable
The comment that is added to the patient report when the threshold is exceeded
The action that the laboratory takes when the threshold is exceeded, such as repeating the test on a different sample or contacting the clinical team

The reporting policy should be documented in the laboratory's standard operating procedures. The policy should be reviewed and approved by the laboratory director. The policy should also be communicated to the clinical team so that the team understands the limitations of the assay.

The reporting policy should be applied consistently to all patient samples. The laboratory should use the hemolysis index, the lipemia index, and the bilirubin index to identify samples that exceed the threshold. The indices are typically reported by the analyzer and are based on the absorbance of the sample at specific wavelengths.

The Role of the Interference Threshold in Assay Validation

The interference threshold is a key component of the assay validation. The threshold defines the conditions under which the assay produces reliable results. The threshold should be included in the validation report and should be used to define the assay's limitations.

The threshold should also be used to guide the selection of patient samples for the assay. The laboratory should not report results for samples that exceed the threshold. The laboratory should instead request a new sample or use an alternative method.

The threshold should be reviewed periodically. The laboratory should repeat the interference screening when the assay is modified, when the reagent lot changes, or when the instrument is changed. The threshold should also be reviewed when the laboratory receives a new lot of the reagent or when the manufacturer updates the assay.

The Interference Screening and the Laboratory Quality System

The interference screening is a component of the laboratory quality system. The screening should be performed in accordance with the laboratory's quality management plan. The screening should be documented and the records should be retained for the period required by the laboratory's quality system.

The laboratory should also include the interference screening in its quality improvement activities. The laboratory should review the interference screening results periodically to identify trends or changes in the assay performance. The review should be documented and should be used to improve the assay.

The laboratory should also consider the interference screening in the context of the laboratory's accreditation. The accreditation bodies, such as the College of American Pathologists and the Joint Commission, require the laboratory to validate the assay and to document the validation. The interference screening is a component of the validation and should be included in the accreditation documentation.

The Interference Screening and the Clinical Team

The laboratory should communicate the interference screening results to the clinical team. The communication should include the interferents tested, the thresholds, and the reporting policy. The communication should be in a format that is understandable to the clinical team.

The laboratory should also provide the clinical team with the information about the clinical significance of the interference. The clinical team should understand that the interference can affect the interpretation of the patient results. The clinical team should also understand the actions that the laboratory takes when the threshold is exceeded.

The communication should be documented. The laboratory should maintain a record of the communication with the clinical team. The record should include the date of the communication, the content of the communication, and the names of the individuals who participated in the communication.

The Interference Screening and the Manufacturer

The laboratory should review the manufacturer's interference data. The manufacturer may have performed interference testing during the development of the assay. The laboratory should compare the manufacturer's data to the laboratory's own screening results.

The comparison should be documented. The laboratory should note any differences between the manufacturer's data and the laboratory's data. The differences may be due to the differences in the sample preparation, the concentrations tested, or the acceptance criteria.

The laboratory should also contact the manufacturer if the screening results are unexpected. The manufacturer may be able to provide additional information about the interference or the assay design. The laboratory should document the communication with the manufacturer.

The Interference Screening and the Regulatory Requirements

The laboratory should follow the regulatory requirements for the assay validation. The laboratory should be accredited by a recognized body, such as the College of American Pathologists or the Joint Commission. The laboratory should also follow the Clinical Laboratory Improvement Amendments (CLIA) regulations for quality control and validation.

The laboratory should also be aware of the regulatory requirements for the reporting of the interference. The laboratory should report the interference in the validation report and should include the thresholds and the reporting policy. The laboratory should also report the interference to the clinical team.

The Interference Screening and the Quality Control

The laboratory should include the quality control samples in the interference screening. The quality control samples should be measured in the same run as the interference samples. The quality control results should be recorded and reviewed.

The quality control samples should be at the same analyte concentration as the baseline pool. The quality control samples should also be at the same concentration as the spiked samples. The quality control samples should be used to verify the assay performance during the screening.

The laboratory should also monitor the quality control results over time. The laboratory should review the quality control results for the assay on a regular basis. The review should identify any trends or issues in the assay performance.

The Interference Screening and the Assay Validation

The interference screening is a component of the assay validation. The validation should include the interference screening, the precision, the accuracy, and the linearity. The validation should be documented in the validation report.

The validation report should include the interference screening results. The report should include the interferents tested, the concentrations used, the bias, and the interpretation. The report should also include the thresholds and the reporting limits.

The validation report should be reviewed and approved by the laboratory director. The report should be stored in the laboratory quality system. The report should be available for review by the accreditation bodies.

The Interference Screening and the Clinical Decision

The interference screening is a component of the clinical decision. The laboratory should provide the clinical team with the information about the interference. The clinical team should use the information to interpret the patient results.

The clinical team should also use the information to decide whether to repeat the test or to use a different method. The clinical team should also use the information to decide whether to request a new sample.

The laboratory should provide the clinical team with the information in a format that is understandable. The laboratory should also provide the clinical team with the information in a timely manner.

The Interference Screening and the Laboratory Information System

The laboratory should integrate the interference screening results into the laboratory information system. The system should be used to flag the samples that exceed the interference threshold. The system should also be used to add the comment to the patient report.

The laboratory should configure the system to flag the samples based on the hemolysis index, the lipemia index, and the bilirubin index. The system should also be configured to add the comment to the patient report when the threshold is exceeded.

The laboratory should test the system to ensure that the flagging and the comment are working correctly. The laboratory should also test the system to ensure that the comment is added to the correct patient report.

The Interference Screening and the Laboratory Staff

The laboratory staff should be trained on the interference screening. The staff should be trained on the preparation of the interference samples, the measurement of the analyte, and the interpretation of the results. The staff should also be trained on the reporting policy.

The training should be documented. The laboratory should maintain a record of the training. The record should include the date of the training, the content of the training, and the names of the staff who completed the training.

The laboratory should also provide the staff with the opportunity to ask questions about the interference screening. The staff should be able to ask questions about the preparation, the measurement, and the interpretation. The staff should also be able to ask questions about the reporting policy.

The Interference Screening and the Laboratory Director

The laboratory director is responsible for the interference screening. The director should review the screening results and the validation report. The director should also approve the reporting policy.

The director should also be responsible for the communication with the clinical team. The director should communicate the interference screening results to the clinical team. The director should also communicate the reporting policy to the clinical team.

The director should also be responsible for the review of the interference screening results. The director should review the results on a regular basis. The director should also review the results when the assay is modified.

The Interference Screening and the Clinical Laboratory

The interference screening is a component of the clinical laboratory. The laboratory should use the screening to ensure the reliability of the assay. The laboratory should also use the screening to ensure the quality of the patient results.

The laboratory should also use the screening to ensure the safety of the patient. The laboratory should not report the results that are affected by the interference. The laboratory should also not report the results that are not reliable.

The laboratory should also use the screening to ensure the compliance with the regulatory requirements. The laboratory should also use the screening to ensure the compliance with the accreditation requirements.

The Interference Screening and the Future

The interference screening is a component of the assay validation. The laboratory should continue to use the screening to ensure the reliability of the assay. The laboratory should also continue to use the screening to ensure the quality of the patient results.

The laboratory should also continue to use the screening to ensure the safety of the patient. The laboratory should also continue to use the screening to ensure the compliance with the regulatory requirements.

The laboratory should also continue to use the screening to ensure the compliance with the accreditation requirements. The laboratory should also continue to use the screening to ensure the compliance with the clinical requirements.